Continuous laminating machines operate preferably with endless impregnation bands of steel or a similar suitable material in such a way that these bands, deflected over rollers, are arranged so that their outsides compress and harden the top or bottom of the impregnated objects under the influence of pressure and temperature. During this process, a negative of the band surface is reproduced on the laminate surface.
To form the reaction zone, a gas or liquid-filled cusion is provided on the two band insides facing each other; this cushion is sealed from the outside against pressure medium losses by gasket sliding on the band insides. This arrangement, representing the state of the art, is known from the U.S. Pat. No. 2,135,763 and from the German Laid-Open Document 24 21 296.
If continuously operating laminating machines with output figures are to be provided which appreciably exceed the output of discontinuously operating installations, because of the time dependence of the hardening processes taking place in the laminate under the influence of heat, long reaction zones and hence long sealing gaps parallel to the feed direction result.
Since with the temperatures above 160 degrees C. customary in hardening, the selection of materials suitable for assuming the sealing function is very small, one must also use those whose friction coefficients are comparatively high. The friction forces occurring with the sliding movement between band rear side and slide sealing material lead to tensile and shear loads which may deform or destroy the seals unduly and set disturbing limits for the application of higher reaction pressures.